In Situ Measurement of Vapor Cell Temperature in Optically Pumped Magnetometer Based on Light Absorption

Optically Pumped Magnetometer (OPM) is an emerging non-invasive biological magnetic imaging sensor. The vapor cell, its core component, requires stable temperature control to achieve ultra-high sensitivity in weak magnetic field detection. This paper presents a full-time, magnetic-field-free temperature measurement scheme for atomic vapor cells, employing an light absorption model that converts light intensity variations into temperature readings. First, we enhance the conventional light absorption temperature measurement model by incorporating the influences from static and modulated magnetic fields. This model modification enabled full-time temperature control achieving a 0.72°C reduction in measurement error. Subsequently, we experimentally quantify and analyze the temperature control performance under different incident light intensities and across various OPM configurations. Furthermore, cross-validation with platinum resistance temperature measurements demonstrates comparable temperature control performance of our proposed method. Most importantly, replacing platinum resistance sensors with our light absorption method enhances the OPM’s sensitivity by 2.83 fT/√Hz.